John and Pat are identical twins with identical DNA. John works in a movie theater, and Pat works as a lifeguard. They have very different skin pigmentation. Which is the best explanation of the difference?

Skin color is a polygenic trait, meaning many genes contribute to it. Environmental factors can also affect pigmentation: a lifeguard is likely to spend more time in sunlight than someone working in a movie theater, and sun exposure can darken the skin. This makes “Skin color, a polygenic trait, is also determined by environmental factors” the best explanation.

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